1. Field of the Invention
This invention relates to shoe manufacturing machinery, and more particularly to an apparatus for applying heat and pressure to a shoe upper for molding thereof.
2. Description of the Prior Art
Shoe manufactures have long used pressure and/or heat in one arrangement or another to form shoe uppers to specific contours of toe or heel portions of a foot. U.S. Pat. No. 2,983,934 describes an inflatable die arrangement to shape an upper about a heated heel mold. This is an early attempt to use heat and pressure to conform an upper about a mold. It is more complicated and hence expensive than what has been developed since. Other inventors using just pressure, as shown in U.S. Pat. No. 3,017,645, form an upper about a heel die, wherein rigid wings that collectively define the surface of the heel, pivot about the heel of the mold and force the upper material thereto. A still further attempt at upper molding and also back seam pressing is shown in U.S. Pat. No. 3,039,288 wherein a heated convex form mates with a heated concave form, with a back seam stitched upper pressed therebetween. This method is costly using built-in heaters with each mold, since separate molds are necessary for variations in shoe size or style, and the die members are susceptible to wear. A recent U.S. Pat. No. 3,464,073, describes a flexible band arrangement comprised of elastomeric material having radiant heating elements disposed adjacent the band but lacking a powdered metallic filler.
The mold members, or dies, exemplified by the above cited examples, should be flexible to permit a slight yielding when pressed and they should conduct heat while not permitting excessive elongation during long periods of use. Some materials used in dies or pressure bands lack good heat transfer characteristics and have "sticky" properties. That is, the upper material and/or the color of upper material adheres with the band, and undesirably transfers it to the next upper being operated upon.
The present invention is designed to overcome the above cited shortcomings of the prior art.